The families of six coal miners killed in a 1983 underground explosion in Southwest Virginia sued the company that owned the mine yesterday for $100 million, alleging that it conspired with a state inspector and two employes to obstruct safety measures at the site.

The complaint, filed in Wise County Circuit Court on the eve of the second anniversary of the blast, included as plaintiffs two other miners who were severely injured in the methane gas explosion, Virginia's worst mine disaster in 25 years.

The lawsuit alleged that Clinchfield Coal Co. conspired with chief Virginia mine inspector Harry D. Childress and the two employes to keep federal and state safety enforcement at McClure No. 1 mine "extraordinarily lax and weak."

Childress and the workers, John W. Crawford and Monroe L. West, both former federal mine inspectors, were named as defendants in the complaint, along with Pittston Co., Clinchfield's corporate parent. None of the men was available for comment yesterday. A spokeswoman for Greenwich, Conn.-based Pittston said the company would have no immediate comment.

The lawsuit alleged that company officials knew the mine leaked between 2 million and 4 million cubic feet of volatile methane gas every 24 hours, but neglected to take proper safety precautions to protect mine workers from the threat of an explosion.

The blast ripped through the mine at 10:15 p.m. on June 21, 1983, killing seven miners and severely burning three others. The family of one dead miner and one of those injured are not parties to the lawsuit.

The complaint alleged that Pittston actively sought the appointment of Childress, a former Pittston employe at the McClure mine, to the post of chief mine inspector by Gov. Charles S. Robb and that Pittston had promised Childress a job "whenever" he chose to leave state employment.

As a result, Pittston exercised "undue and improper influence" over state mine safety enforcement, the lawsuit alleged.

The Washington Post revealed in July 1983 that Childress owned about $20,000 worth of Pittston stock while working as chief mine inspector. Childress later sold the stock and was removed from a state inspection of the accident. He remained in his $35,000-a-year state safety post.

The company's purpose in hiring Crawford and West away from the U.S. Mine Safety and Health Administration was to give the firm "personnel who would wield influence and power over their former subordinates and successors" at the agency, the lawsuit alleged.

"As a result of their influence," the complaint said, "inspectors were harassed, reassigned and transferred."

According to the lawsuit, Crawford and West "effectively undercut and nullified" federal mine safety measures, obtained safety exemptions for the company, won MSHA approval for safety deviations and departures and reduced or eliminated fines and penalties imposed by the agency.

"As part of an overall plan approved by Pittston," the complaint alleged, "Crawford and West dominated and controlled the operation of the MSHA District 5 office in Norton, Va., vis-a-vis the McClure No. 1 mine and other Clinchfield operations."